Moparts

Alt over charging, need wiring help!

Posted By: express

Alt over charging, need wiring help! - 07/06/14 06:29 PM

70 Duster 340, Volt gauge has been funny for a long time. At idle it would bounce around rapidly between 12 & 14 or so. It speed it would even out.

Last summer I did the bulk head bypass a per Mad Wiring & by passed the amp gauge.

Now it is charging 15 volts all the time! If I unhook the regulator it stops charging.

I have replaced the alt, reg, grounded the reg to the batt but no change.

All of the under hood wiring was moved under the dash years ago to clean up the engine side, so it not as easy to get to.

Something is crossed but I can not figure out, help!
Posted By: cjskotni

Re: Alt over charging, need wiring help! - 07/06/14 06:40 PM

I know you said you have a good ground on the regulator but double check with an ohm/volt meter and make sure.

Next, I would take a 10ga or higher jumper wire and go from the alternator CASE to a known good ground (or better the negative battery terminal). When you connect this wire, see if your charging voltage doesn't go down a bit. Ideally you want a charging voltage of ~ 14.5V or so. You aren't too far off but 15V is right on the edge where you may be blowing bulbs prematurely and hurting the gauges over the long term.

If the charging voltage does drop when the jumper is connected, your alternator case itself has a poor ground. To test further, take a second jumper wire and connect the VR body to the alternator case with these 10ga jumpers. This will ensure you have a good ground and rule out grounding issues.

Let us know how it goes and good luck!
Posted By: RapidRobert

Re: Alt over charging, need wiring help! - 07/06/14 08:19 PM

flat 70 & up reg/2 field alt system correct? Confirm that the reg is grounded but if I am reading this right it started when you did the Madd bypass? so I will assume the reg is grounded but do check it. Also assuming tha batt is fully charged (it should be by now ) and that the batt is good (not sulphated/bad cell). Take off both field wires from the alt and take off the triangle green/blue wire connector from the reg. with some jumper wires jump 12V to both the reg top (blue wire) terminal AND to one of the alt field terminals and with another jumper connect the other alt field terminal to the other reg (side) terminal (the green wire circuit) & see if it charges normally at a fast idle. If so this tells you the hard components are OK & that it is a wiring issue. Holler back when you can and if this is an earlier setup (box reg/1 field terminal alt or 2 field terminal alt with 1 field terminal grounded) holler back. Most overcharging is a bad or not grounded reg or a grounded brush assy on the green wire side or the green wire/its end terminals grounded). Easier yet since it stops charging when you pull the reg triangle connector you might pull it then jump fire right there to the blue wire reg nub terminal & if it still overcharges then find where the green wire from reg to alt/green wire brush assy is grounded or a bad or not grounded reg. holler back. EDIT this ain't resulting from the Madd bypass but it sounds like all that other major wiring changeover was done at the same time (when the problem started). & also holler if this is the earlier (box reg) setup
Posted By: 383man

Re: Alt over charging, need wiring help! - 07/06/14 09:20 PM

If its a factory 2 field alt with the electronic regulator the reg has to be grounded for it to charge at all since the reg grounds the field to make it charge. Many times on that system it is the blue wire at the reg either lost volts or is not making contact on the reg and it does not know what battery volts is so it keeps on charging. I have seen alot of them break the wire on the inside by the reg connector. The wire itself is still hooked up but the wire strands break inside the insulation and the reg does not see battery volts. Thats the blue wire at the reg as it should be 12 volts with the key on and when running it should run around 13 to 14.5 volts the same as its charging. You said it stops charging with the reg unplugged and you replaced the reg so I would check that blue volt sense wire real close on the reg. Ron
Posted By: RapidRobert

Re: Alt over charging, need wiring help! - 07/06/14 09:24 PM

Quote:

If its a factory 2 field alt with the electronic regulator the reg has to be grounded for it to charge at all since the reg grounds the field to make it charge. Ron

I learned sumpin new today , yes it would HAVE to be grounded if it IS charging. Makes perfect sense
Posted By: express

Re: Alt over charging, need wiring help! - 07/06/14 09:53 PM

It is a flat regulator & 2 field alternator.

There was some kind of problem before I did the Madd bypass, that is why I did it. But now it is undrivable.

I have grounded alt & reg to the battery before, which is in the trunk but no difference.

I am going out & test what you recommended.
Thanks,
Posted By: express

Re: Alt over charging, need wiring help! - 07/06/14 10:31 PM

Update: Volts are bouncing rapidly between 14 & 16 @ idle & steady 14.5 @ 2000.
Posted By: HemiRick

Re: Alt over charging, need wiring help! - 07/06/14 10:47 PM

Quote:

Update: Volts are bouncing rapidly between 14 & 16 @ idle & steady 14.5 @ 2000.



Thats a normally functioning system sound like you fixed it
Posted By: express

Re: Alt over charging, need wiring help! - 07/06/14 11:37 PM

Quote:

flat 70 & up reg/2 field alt system correct? Confirm that the reg is grounded but if I am reading this right it started when you did the Madd bypass? so I will assume the reg is grounded but do check it. Also assuming tha batt is fully charged (it should be by now ) and that the batt is good (not sulphated/bad cell). Take off both field wires from the alt and take off the triangle green/blue wire connector from the reg. with some jumper wires jump 12V to both the reg top (blue wire) terminal AND to one of the alt field terminals and with another jumper connect the other alt field terminal to the other reg (side) terminal (the green wire circuit) & see if it charges normally at a fast idle. If so this tells you the hard components are OK & that it is a wiring issue. Holler back when you can and if this is an earlier setup (box reg/1 field terminal alt or 2 field terminal alt with 1 field terminal grounded) holler back. Most overcharging is a bad or not grounded reg or a grounded brush assy on the green wire side or the green wire/its end terminals grounded). Easier yet since it stops charging when you pull the reg triangle connector you might pull it then jump fire right there to the blue wire reg nub terminal & if it still overcharges then find where the green wire from reg to alt/green wire brush assy is grounded or a bad or not grounded reg. holler back. EDIT this ain't resulting from the Madd bypass but it sounds like all that other major wiring changeover was done at the same time (when the problem started). & also holler if this is the earlier (box reg) setup



I did the jump wires & it was not charging at all. IT ALSO WOULD NOT SHUT off, had to turn the batt off.
Posted By: Pacnorthcuda

Re: Alt over charging, need wiring help! - 07/06/14 11:47 PM

I would remove and clean the brushes and their ceramic holders then reinstall. May not be the problem but very easy to do.
Posted By: RapidRobert

Re: Alt over charging, need wiring help! - 07/06/14 11:55 PM

If the alt/reg are good/grounded and you jump fire to them directly and the green wire connecting them has continuity then they MUST charge. We're missing something. We need a diagram of how things are wired now to proceed. The most common prob with batt in the trunk is too small of cables but we have other issues that must be taken care of first. Post a diagram when you can. What I prefer with a batt in the trunk is to run the 2/0 positive cable up to the starter large lug (hot all the time but welding cable ain't gonna short (has very thick insulation) & you dont lay it next to sharp edges when you are routing it front to rear) then run an 8 ga from starter large lug to starter relay large lug & ammeter in series in that line between the two then run a line from the large starter relay lug to the bulkhead/interior to power everything. I run the alt to the starter relay large lug. EDIT "it wont shut off". The ign sw ign1 (run) terminal should be wired to open/close current to the reg/alt/coil/ECU. I should bone up on the Madd conversion but something did get crossed there. Their conversion is sound if you dont mind losing the ammeter function and have accessories that are drawing alot of current from the batt side and you dont want to route all the current to replenish the batt from alt to bulkhead then inside the dash then thru bulkhead again then back to battery. I prefer to bypass the 2 main in/out wires in the bulkhead/relay add ons directly to the source (the alt) that will be powering them and keeping my ammeter (plus adding a voltmeter to switched 12V)
Posted By: express

Re: Alt over charging, need wiring help! - 07/07/14 12:01 AM

ok, swapped batt because it not start & volts never settle down. Always bouncing 14-16.

Not sure what you mean jumping it @ the reg.

Batt wire is double aut 0
Posted By: RapidRobert

Re: Alt over charging, need wiring help! - 07/07/14 12:15 AM

Quote:

Not sure what you mean jumping it @ the reg.

Jumping 12V directly to the top nub in the reg (with it facing up like a pyramid). That is the blue wire circuit
Posted By: express

Re: Alt over charging, need wiring help! - 07/07/14 12:19 AM

Quote:

Quote:

Not sure what you mean jumping it @ the reg.

Jumping 12V directly to the top nub in the reg (with it facing up like a pyramid). That is the blue wire circuit



Ok so jump a 12 v wire to the reg blue & another wire to connect the green wire from the pyramid connector to the reg?
Posted By: RapidRobert

Re: Alt over charging, need wiring help! - 07/07/14 12:26 AM

(have the present connectors all unplugged). yes, jump fire to the top reg terminal AND to either of the alt fields. then with a seperate jumper wire (not connected to any voltage) connect the other reg (side) terminal to the other alt field terminal. Fast idle. If the alt and reg are good (& grounded ) it WILL charge. EDIT but dont we already know it will charge & it's charging too high?
Posted By: express

Re: Alt over charging, need wiring help! - 07/07/14 01:43 AM

I ran a new wire from the alt green to the reg direct but no change.

I had the jumper wires attached to the batt side of the alt. I removed them after the car wouldn't shut off. I thought I had put the batt wire back on the alt but apparently I had not! While checking continunity I bumped the batt wire & it shorted out & smoke came from under the dash, I shut the batt off. Don't now what happened under the dash, all the wires feel ok but I can't get the door open enough to crawl under there, (another car in the way. ) Will look at it some day.
Thanks for the help.
Express
Posted By: RapidRobert

Re: Alt over charging, need wiring help! - 07/07/14 01:54 AM

Mr Murphy does not play nice. Holler when you can & we'll go from there
Posted By: 70HemiGTX

Re: Alt over charging, need wiring help! - 07/07/14 03:05 AM

Look at ALL of your connections at ALL connectors. Especially with the "heavy red" wires. Like steering column, bulkhead, etc. Look for a burned connector. Somewhere you have resistance. Find it, bypass it with same gauge wire and you will not believe how the alt. will settle down.
Posted By: 2BblHarold

Re: Alt over charging, need wiring help! - 07/07/14 03:30 AM

Let's not forget that the ignition switch is in the charging circuit too. I went through all of the above symptoms and fixes before I changed out my switch, easy on a '68. Problem solved.
© 2024 Moparts Forums